NORTHAMPTON — On an early March weekend, as numerous musicians took the stage at venues across the city for the Back Porch Music Festival, some spent a portion of their downtime at Mill River Music and Guitars, relaxing on the store’s couches, surrounded by hundreds of acoustic and electric guitars displayed on the walls.

Yet even as professionals make their way to the guitar shop’s new and expansive 7,500-square-foot showroom and repair space at 135 King St., and local musicians drop by for occasional jam sessions, Mill River Music owners Jon and Nina Aronstein want those who are just starting out, as well as members of the LGBTQ+ community and women who haven’t always received the necessary help to play guitars, to drop in.

“We want everyone to feel welcome here, for everyone to feel really good,” says Nina Aronstein. “We care deeply about the community and everyone coming through the door.”

“We’re trying to be universal in how we treat our customers,” Jon Aronstein said.

The husband-and-wife team say they understand the aim is to serve everybody, from “brand-new beginner to the long-term professional,” as Jon Aronstein puts it.

“We spend a lot of time with our customers,” he said. “Education is a big part of our mission and to help to orient them to their needs.”

Mill River Music opened Feb. 6 at its new location, once the site of Midway Electric Supply Co., more than seven years after opening in a 1,000-square-foot location on Armory Street. That space was so tiny that the store needed six separate storage locations and held periodic “Guitar Bazaar” tag sales.

“It’s been a huge breath of fresh air to move here from a place that was so cramped,” Nina Aronstein said.

Inside the new site, the 20-foot high walls are lined with guitars from Fender, Taylor, Martin, Paul Reed Smith, Eastman and Ibanez, ranging in price from $100 to $300 for the least expensive to a $7,000 acoustic guitar made from the best woods and materials. There is a “boutique” zone of guitars that are more delicate, vintage and collectible. But the Aronsteins note that a good guitar player can make just about any guitar sound good.

Along with the guitars for sale are hundreds of effects pedals used with guitars, along with other instruments, including drums and keyboards, and various accessories.

“Global availability, local heart” is the tagline for the business. “We have big availability with small store vibes,” Jon Aronstein said.

Taking its name from a woodworking business Jon Aronstein ran, and walks the couple took along the banks of the Mill River, Mill River Music began as a loose partnership with Birdhouse Music in 2017 and a $2,000 investment. Jon Aronstein was a luthier at Birdhouse for about six years and previously trained in guitar making in the 1990s, something he continues to dabble in.

“We really wanted to do things a different way,” said Nina Aronstein, who herself plays guitar and is a classically trained soprano.

The couple attributes the exponential growth, having now bought and traded about $4 million worth of guitars, as partially being driven by the pandemic. “During the pandemic we were literally shipping strings to people across the globe,” Nina Aronstein said.

The new space allows Mill River Music to have three designated demo rooms, each with a theme designed by Nina Aronstein, with one focused on the Beach Boys, another on Prince and the third on Dolly Parton. Another room is the dedicated acoustic guitar room.

With nearly a dozen employees on staff, along with two part-time shop dogs, everyone brings experience and knowledge. Four primary technicians handle repairs in what has become a school of luthier training. The projects can range from basic set up, to making a guitar play well and to the customer specification to full reconstruction. “We do everything,” Nina Aronstein said.

Every instrument also gets checked to make sure it is playing well before being sold. “The sheer numbers gives us knowledge you could never get in other contexts,” Jon Aronstein said.

The Aronsteins bought the new building last year, which in recent years had been the site of Anytime Fitness, and then spent several months working with architects and engineers to redo the interior. “We have put all of our human energy and intents into this,” Jon Aronstein said.

Work was coordinated by Florence contractor Douglas Thayer and included the construction of mezzanines where the guitar cases and amp boxes are stored. Dave Lashway cut the trees and fashioned the lumber into the posts holding up the upper level areas.

In the future, the new site could offer performance space and more educational opportunities, especially for those starting out.

Jon Aronstein observes that “Northampton is part of our sauce” and the couple hopes the city remains a heart of New England’s music scene and that live music continues to rebound. They have some confidence this will be the case, demonstrated by events like the Back Porch Festival, the reopening of Iron Horse and the scheduling of events at the Parlor Room, and across the region, such as the concert series at Tree House Brewing in South Deerfield.

“We think music is such a critical part of our society, of being human,” Nina Aronstein said. “It’s really important we support every single customer, supporting them in their hearts, supporting them in getting out of bed in the morning, or supporting them in whatever it is for them.”

Scott Merzbach can be reached at smerzbach@gazettenet.com.